The assumption of noncontextuality (more precisely, preparation noncontextuality [1]}) and linearity applied to the operational equivalences in O2 requires that any noncontextual ontological model must satisfy (see Eq. (REF ))
\(\frac{1}{2} \mu _s(\lambda ) + \frac{1}{2} \mu _{s^\perp }(\lambda ) = \frac{1}{2} \mu _{s^{\prime }}(\lambda ) + \frac{1}{2} \mu _{s^{^{\prime }\perp }}(\lambda ),\) 
